The present invention allows for the recovery of water from exhaust gases of internal combustion engines, such as those found in military vehicles, cars, jeeps and all-terrain vehicles. The goal is to provide a source of water for drinking and for other uses, for example, for army troops in the field or campers in a wilderness area. The composition of engine exhaust emissions vary as a function of fuel type and content, as well as the fuel:air ratio, the type of engine and mode of its operation, and factors such as ignition timing, cylinder design and fuel additives. Although the relative concentrations of various exhaust components may change depending on the mode of engine operation, generally the nature and content of exhaust remains within a predictable range. It would be useful to be able to capture the water vapor found in engine exhaust and turn it into drinkable water, particularly for military operations or travel in hostile environments (e.g., desert areas).
The concentration of water vapor in exhaust gases of either gasoline or diesel engines or turbines ranges up to about 10% by volume. Upon cooling the exhaust gases below its dew point, i.e., about 100° F., water begins to condense from the exhaust. Some gases present in the exhaust, such as oxygen, nitrogen and hydrogen, do not condense. The other exhaust components, such as hydrocarbons, sulfur dioxide, nitrogen oxides, carbon dioxide and particulates and suspended solid matter, and other dissolved organic and inorganic matter (including metals), contaminate the condensed water by dissolving in or condensing with the water vapor and must be removed to obtain a potable water product. The treatment apparatus for the recovery of potable water from the engine exhaust must condense the water vapor, remove the particulates, and purify the water produced therefrom, and do this in an efficient and effective way.
Vehicle exhaust gases and the condensed water produced therefrom are very corrosive. The untreated water that is recovered from exhaust gases generally has a pH of from about 1 to about 3 and, in a high temperature environment, corrosion easily occurs in pits and crevices of heat exchangers, ducting and ancillary equipment used to condense it, as well as the various materials, such as the ion exchange resins, used to purify the water. High exhaust temperatures and the elevated ambient temperatures that prevail under desert/arid conditions exacerbate the rates of chemical attack on materials. Hence, the selection of appropriate materials for the condensation/purification components can be extremely important.
A method and apparatus for recovering potable water from the exhaust gases of an internal combustion engine is described in our earlier International Patent Application WO 02/059043 A2, published Aug. 1, 2002, and in U.S. Pat. No. 6,581,375, Jagtoyen and Kimber, issued Jun. 24, 2003, both incorporated herein by reference. The method disclosed comprises the steps of:                (a) cooling said exhaust gases so as to cause water to condense from them (for example, utilizing heat exchangers);        (b) passing said water through one or more particulate filters having a maximum pore size of from about 0.1 to about 10 microns;        (c) passing said water through one or more activated carbon beds or monolithic activated carbon (a preferred one sequentially combining a wood-based carbon having a majority of pores in the range of from about 17 to about 40 Å, with a coal-based water-treatment carbon having an average pore size of from about 6 to about 20 Å—the wood-based carbon preferably made by phosphoric acid activation and treated to minimize the amount of phosphorous released into the water); and        (d) passing said water through one or more ion exchange resin beds (preferred resins being a mixed bed of highly acidic and strongly basic Type 1 ion exchange resins and/or mixed bed resins exhibiting ultra-low leaching of organics, such as those made for the semiconductor industry, with low organics and particulate contaminants having high cation and anion exchange capacity).The order in which steps (c) and (d) are carried out can also be reversed.        
The present invention provides an improvement on the process and apparatus disclosed in that patent application.